| The low degree of automation of irrigation and imprecision in water supply are the important factors affecting seedling production in forestry,and the important reasons for the low efficiency of water use.Therefore,in this thesis,one year old seedlings of three Phellodendron chinense Schneid provenances were used as materials to conduct water stress experiments through a intelligent irrigation system in order to study the response patterns of seedling growth,antioxidant enzyme activity,osmoregulation capacity and photosynthetic characteristics of Chuan Huang cypress seedlings,and the three Phellodendron chinense Schneid provenances were comprehensively assessed by PAC and subordinate function.We investigated the water demand of Phellodendron chinense,captured the water saving irrigation technology,explored the appropriate automatic irrigation parameters of Phellodendron chinense,and improved the water use efficiency of the Phellodendron chinense seedling culture process using a intelligent irrigation control system under IOT technology.The results of the study have significant theoretical and practical significance in terms of using Phellodendron chinense resources,improving water use efficiency,promoting seedling production efficiency,and industrialised planting.The results of the study revealed that:1.An architectural schematic of the intelligent irrigation system is constructed,including the field monitoring system,data analysis and transmission system,remote control,and visualization.We build a hardware system with the esp32 module as its core and a C language based software system,and the APP is developed with the aid of the blinker platform in order to realize real-time remote viewing and control of the intelligent irrigation system.2.Under the control of the intelligent irrigation system,the net growth in seedling height and diameter of the three Phellodendron chinense Schneid provenances showed a trend of first increasing and then decreasing as the water supply was decreased,and the net growth in seedling height and diameter of Phellodendron chinense Schneid seedlings was greatest when soil water content reached between 60 and 70%of the maximum soil water holding capacity.The net growth in height and diameter of seedlings gradually decreases with decreasing water supply.,but the net growth in seedling height and diameter from Hunan Xiangxi was higher than that from Chongqing Jiangjin and Hubei Enshi.3.Excess water supply(water supply makes soil water content more than 70%of soil maximum holding water)and inadequate water supply(water supply makes soil water content less than 60%of soil maximum holding water)can result in an increase in the activity of antioxidant enzymes,malondialdehyde content,conductivity,and so on.Excessive water supply led to high malondialdehyde content and insufficient water supply led to high content of osmosis regulators in the seedlings,Antioxidase activity and osmolytes conte in seedlings from Hunan Province were higher than those from Enshi in Hubei and Jiangjin in Chongqing.Water supply makes soil water content at 60-70%of soil maximum water holding is the irrigation threshold of intelligent precision irrigation system,hunan xiangxi provenance is more drought tolerant than enshi in hubei and jiangjin in chongqing.4.Seedling photosynthetic efficiency was significantly lower when water supply was too high or too low than when soil water content was kept at 60 to 70%of maximum soil water retention.With the decrease of water supply,the parameters such as net photosynthesis rate,stomatal conductivity,transpiration rate,electron transfer rate,photochemical quenching coefficient,practical photochemical quantum efficiency and photosynthetic pigment content all decreased significantly.In the context of water scarcity,the photosynthetic efficiency of the Hunan Xiangxi provenance is obviously higher than that of the Enshi provenance in Hubei and the Jiangjin provenance in Chongqing..5.We conclude that maintaining soil water content at 60 to 70%of maximum soil retention is the optimum irrigation threshold for seedling production of Phellodendron chinense Schneid under intelligent irrigation systems.Since the comprehensive evaluation values of Chongqing Jiangjin,Hunan Xiangxi,and Hubei Enshi were 0.457,0.637,and 0.448,respectively,the drought strength of the three provenances was Hunan Xiangxi>Chongqing Jiangjin>Hubei Enshi in the order of their values. |
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